The Atlantic Tech Transfer Team for Apiculture has now completed their regional Varroa mite survey for 2025. This is the second season of data collection for the survey, and the team intends to conduct one more season’s worth of sampling in 2026. Continue reading this week’s blog to learn more about late-season trends in Varroa mite populations across our Maritime region, and for insight to how this year’s mite levels compare to 2024.
Late-Season Regional Trends in Varroa Mite Populations
The
third, and final, trial of the 2025 regional Varroa mite
survey consisted of 15 beekeepers (8 in Nova Scotia, 6 in New Brunswick and 1
on Prince Edward Island). The third trial took place between August 28 and
September 26, and consisted of 58 honey bee samples. These samples are all from
commercial beekeepers who provided pollination services earlier in the season. Overall,
the average mite load for trial 3 was 1.17% infestation rate per sample (Figure
1), 54% of samples had detectable mites, and 19% of samples had a mite load
greater than 1% (Figure 2). The average number of bees per sample for trial 3 was
353, with a target sample size of 300.
In
comparison, in 2024, the average mite load per sample for trial 3 (September 3,
2024 – September 24, 2024) was 1.28% (Figure 1), 68% of samples had detectable
mites, and 22% samples had a mite load greater than 1% (Figure 2). The slight
difference in mite levels between 2024 and 2025 is not statistically
significant, and may reflect the normal range of mite levels across our region.
A main priority of the survey is to establish a baseline of the region’s mite
levels across the beekeeping season.
 |
Figure 1. Average Varroa mite load per sample of honey bees in the Maritime region across the beekeeping season with a total of 23 commercial beekeepers represented in 2024 and 2025. Trial one occurred during April through to June, trial two occurred during July and August, and trial three occurred during August and September. Error bars represent standard deviation.
Varroa
mite levels significantly increase throughout the beekeeping season as
reflected by the results of the survey (Figure 1 and 2). This makes early
spring monitoring and treatment for Varroa mites crucial, because the
population can quickly get beyond the economic threshold if waiting until the
fall to treat colonies again.
Additionally,
it is important that beekeepers understand that 0% Varroa mite load, as
determined by an alcohol wash, does not mean that no Varroa mites are present
within the colony. There is always a background population of Varroa mites
within a single colony and, without frequent and representative monitoring,
undetected population grows will quickly increase to beyond treatment
thresholds.
To
effectively manage Varroa mites beekeepers need to practice integrated pest
management (IPM). A crucial aspect to IPM is monitoring for mites throughout
the beekeeping season, and before and after treatments. Within an operation,
and within a single apiary, Varroa mite levels can vary. This means it is
important for beekeepers to have good sampling representation in each of their
apiaries to be proactive in identifying Varroa mite population spikes. A colony
with high Varroa mite levels can quickly impact other colonies within the
apiary and lead to Varroa mite spread throughout an entire operation or region.
Beekeepers should manage their mite levels to be below 1% all throughout the
beekeeping season. Beekeepers should also start late-summer/early-fall mite
treatments as soon as possible when levels are at or exceeding 1% to help
ensure healthy winter bees with low virus loads.
For
treatment, beekeepers should always treat all colonies within an apiary, and it
is essential to follow the manufacturer instructions, which includes the
timing, dosage, and application of treatment.
For
questions regarding mite management and treatment please reach out to the ATTTA
team. We would like to thank all beekeepers who participated in the survey for
2025. We will be reporting on the complete survey and other Varroa mite testing
later this year.
Connecting with ATTTA Specialists
If you’d like to connect with ATTTA specialists or learn more about our program, you can:
visit our website at https://www.perennia.ca/portfolio-items/honey-bees/
Email attta@perennia.ca